Kuraray Noritake Dental Developed New Flexible Zirconia

  Kuraray Noritake Dental Developed New Flexible Zirconia   A world first! Combining high strength, superior toughness and hydrothermal                                   resistance                Expanding into dental materials and other fields  Business Wire  TOKYO -- June 3, 2014  Kuraray Noritake Dental Inc., a joint venture of Kuraray Co., Ltd. (TOKYO:3405) and Noritake Co., Limited (TOKYO:5331), has developed a highly durable zirconia that possesses both high strength and superior toughness. Kuraray Noritake Dental is pursuing the marketing of this new and unique product in the dental material and other fields.  The photo shows a side view of a 0.2 mm thickness by 4.0 mm width plate of the new product being sub ...  The photo shows a side view of a 0.2 mm thickness by 4.0 mm width plate of the new product being subjected to a three-point flexural strength test. (Photo: Business Wire)  1. Characteristics of the Material  Kuraray Noritake Dental developed the new durable zirconia, improving the raw materials and manufacturing processes, aiming to develop a highly reliable ceramic material. Kuraray Noritake Dental succeeded in developing a new type of zirconia that has both higher flexural strength and fracture toughness^1 and, when exposed to hydrothermal condition, its crystal structure does not change to a monoclinic phase, a common cause of compromised strength. In addition, the product does not need to be subjected to Hot Isostatic Pressing.  The yttria partially stabilized zirconia currently in wide use is very strong, however, it possesses the fragility which is characteristic of ceramics. Zirconia is also known to gradually weaken over time as the crystal structure changes from a tetragonal phase to a monoclinic one when exposed to hydrothermal condition^2.                                                                    Comparison with Existing Products                                  Examined Property       Unit                      Conventional   New Product                                                     Zirconia Three-point flexural     MPa (megapascal)           900–1,200      1,500 strength                          MPa√m (megapascal square Fracture toughness       root                       4–5            12                          meter) Ratio of monoclinic phase        % (percent)               80            <1 (accelerated aging test) The above based on comparative data obtained by Kuraray Noritake Dental.   Since the new product has higher flexural strength and fracture toughness than conventional zirconia, it exhibits such characteristics as the ability to withstand being deformed to a high degree without fracturing.  The conventional zirconia fractured at the 4 mm mark compared with the starting horizontal position. The new product, however, maintained its integrity until it was pressed into a 6 mm arc, confirming its high fracture toughness.  2. Potential Applications  Mainly dental materials, prosthetic joints and general industrial applications.  About Kuraray Noritake Dental  Kuraray Noritake Dental Inc. was launched with the integration of Kuraray Medical Inc. and Noritake Dental Supply Co., Ltd. in 2012. The two companies, both of which have enjoyed the leading market share in Japan for the advanced technological capabilities in their respective business fields (resin based dental materials and dental ceramics), decided to join forces with an eye to making even greater strides in expanding their domains and creating new fields in the future.  Note to editors: 1. Resistance to extending cracks: higher number means more difficult to break 2. Tested under ISO 13356:2008  Photos/Multimedia Gallery Available: http://www.businesswire.com/multimedia/home/20140603007075/en/  Multimedia Available:http://www.businesswire.com/cgi-bin/mmg.cgi?eid=50878476&lang=en  Contact:  Kuraray Co., Ltd. Takeshi Hasegawa, +81-3-6701-1080 kuraraykoho@kuraray.co.jp  
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